Commercial optical fiber connector assemblies (“connector assemblies”) are used to couple optical fibers together so that light transiting from a bundle of one or more fibers in one end of the connector assembly will pass through the connector assembly to fibers or a device connected to the other end of the connector assembly. Such connector assemblies typically include a ferrule through which the optical fiber(s) is inserted before assembly of the ferrule and optical fiber(s) within the connector assembly. The ferrule holds the fiber(s) in a precise position and ensures that when the connector assembly is attached to a mating connector assembly or some other device, the fiber(s) of the connector assembly are held in consistent alignment.
Many applications today require connector assemblies containing multiple fibers (“multi-fiber connector assemblies”). Many commercially available multi-fiber connector assemblies today—such as that shown in U.S. Pat. No. 5,214,730—provide connections for fiber arrays of between 2 and 12 fibers arranged in a single row (although some commercial 2×12 configurations are available). In addition, other types of commercial connectors for small arrays of fibers (i.e., less than 12) are available or have been proposed, for example, as shown in U.S. Pat. No. 5,743,785.
These multi-fiber connector assemblies typically use a common type of ferrule commercially available from, among others, US CONEC LTD. and ALCOA FUJIKURA LTD. These ferrules are generally quite small in size, on the order of about 2 mm (2,000 microns) high, 6 mm (6,000 microns) wide and 8 mm (8,000 microns) deep, and have a face portion of at least 3 mm (3,000 microns) thick to support and hold the optical fibers. These ferrules typically contain an array of fiber holes (generally linear or rectangular), each sized to accept a single optical fiber, spaced apart from one another by a center-to-center distance (“pitch”) of approximately 250 microns (± a few microns of manufacturing tolerance).
To facilitate insertion of the individual fibers into the fiber holes, these ferrules typically include a guide groove or internal guiding structure for each fiber hole. These guide grooves are typically about 1.5 mm (1,500 microns) long, although they can be longer or shorter, and may be stepped so that each row of guide grooves is slightly longer than the row of guide grooves immediately above it. Thus, to assemble these ferrules, the individual fibers of a group (e.g., row)—typically a ribbon or cable of fibers—are manually inserted into an opening in one end of the ferrule where they are separated and manually placed into their respective guide grooves to direct the fibers toward their respective fiber holes in the ferrule. Each fiber within the group or row is then manually inserted through its respective fiber hole at the other end of the ferrule and the assembly process continues for the next group or row of fibers. Once all of the fibers have been manually inserted within their respective fiber holes in the ferrule, then a material, such as an epoxy, is typically inserted into the ferrule to fix the fibers firmly in place.
Because of the increased need among users in the fiber optic field for larger groups or arrays of fibers, there is demand within the industry for single connector assemblies capable of handling arrays of fibers in excess 1×12 or 2×12 (e.g., 5×12, 5×16, 6×12, or N×M arrays). To address this industry need, the assignee of this application has developed a ferrule for large format arrays that is both cost-effective to manufacture and is reproducible to the required tolerances for a multi-fiber connector assembly. This large format array ferrule is described and illustrated in the co-pending, commonly assigned U.S. application Ser. No. 10/090,880 entitled “OPTICAL FIBER FERRULE,” filed Mar. 4, 2002, which is incorporated by reference herein in its entirety.
In addition to satisfying the need for a multi-fiber connector assembly capable of handling a large format array of fibers, this ferrule completely or almost entirely eliminates the need for guide grooves or other internal guiding structures for directing each fiber towards its respective fiber hole in the ferrule. However, there are no procedures for insertion of the fiber into a N×M array ferrule with multiple rows (beyond two) containing no internal guiding structures. Without such internal guiding structures, insertion of the fiber into a N×M array ferrule using current conventional procedures practiced by connector companies is not possible.